Abstract
AbstractGrain boundary melting and its effect on hot cracking in the weld heat-affected zone (HAZ) have been investigated in the investment cast billet of a two-phase (γ + γ′) nickel aluminide alloy (Ni74.48Al16.98Cr8.02Zr0.51B0.10), designated as IC-218. Due to enrichment of Zr, which can form eutectic alloys with Ni, the dendritic boundaries melted incipiently at 1150°C. Under thermal stresses during welding the molten layers often opened up producing liquation cracks at the boundaries in the HAZ. Annealing at 1100°C in argon for 23 h prior to welding reduced the incipient melting temperature to 1125°C and increased the propensity of liquation cracking in the HAZ.
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